Geographic Concerns on Flood Climate and Flood Hydrology in Monsoon-Dominated Damodar River Basin, Eastern India

Table 9

Pre-dam and post-dam comparison of standard peak flood discharge and estimated runoff of variable return period using Gumbel distribution.

return period (years)	Reduced variate	Pre-dam period			Estimated; runoff; (mm)	Post-dam period			Estimated; Runoff; (mm)
				(m^3 s^−1)				(m^3 s^−1)
5	1.5	= 0.5296; = 1.0864; = 24	0.893	11,728	50.87	= 0.54854; = 1.16066; = 50	0.819	5,352	23.21
10	2.25		1.583	14,317	62.10		1.465	6,796	29.48
20	2.97		2.246	16,805	72.89		2.086	8,184	35.50
50	3.9		3.102	20,016	86.81		2.887	9,974	43.26
100	4.6		3.746	22,433	97.30		3.49	11,322	49.10
150	5.3		4.391	24,853	107.80		4.093	12,670	54.95

Note: : frequency factor of Gumbel distribution, : estimated or projected peak discharge, : mean of peak discharges, : standard deviation of distribution, and : number of variables.